Room-temperature magnetoresistance in an oxide material with an ordered double-perovskite structure

Abstract

Colossal magnetoresistance—a huge decrease in resistance in response to a magnetic field—has recently been observed in manganese oxides with perovskite structure. This effect is attracting considerable interest from both fundamental and practical points of view¹. In the context of using this effect in practical devices, a noteworthy feature of these materials is the high degree of spin polarization of the charge carriers, caused by the half-metallic nature of these materials²⁰,²¹; this in principle allows spin-dependent carrier scattering processes, and hence the resistance, to be strongly influenced by low magnetic fields. This type of field control has been demonstrated for charge-carrier scattering at tunnelling junctions²,³ and at crystal-twin or ceramic grain boundaries⁴,⁵, although the operating temperature of such structures is still too low (⩽150 K) for most applications. Here we report a material—Sr₂FeMoO₆, an ordered double perovskite⁶—exhibiting intrinsic tunnelling-type magnetoresistance at room temperature. We explain the origin of this behaviour with electronic-structure calculations that indicate the material to be half-metallic. Our results show promise for the development of ordered perovskite magnetoresistive devices that are operable at room temperature.